1. Field of the Invention
The invention relates to a connector for a towing vehicle.
2. Description of the Related Art
A connector for a wire harness of a towing hitch electrically connects wiring harnesses of a vehicle and a to-be-towed object, such as a trailer to each other. Such a connector is standardized in its configuration and size by such as SAE (US Society of Automotive Engineers) or JIS (Japanese Industrial Standard). Thus, compatibility among various kinds of vehicles is secured. In United States of America, the commercially available xe2x80x9cSeven-Way Connectorxe2x80x9d commercially is the standard in the industry.
The xe2x80x9cSeven-Way Connectorxe2x80x9d is compatible with the cylindrical connector at the trailer side in the connection therebetween. There are three kinds of conventional xe2x80x9cSeven-Way Connectorsxe2x80x9d.
The first conventional connector for the towing vehicle is shown in FIGS. 4 and 5. This connector has wires 1 that extend from the towing vehicle body and a screw 2 is tightened to fix the electric wires 1 extending from the towing vehicle body to terminals 3a that are to be inserted into the connector body 3. Thus, the electric wires are connected to the terminals. However, no waterproof measure is taken in the construction of the connector for the towing vehicle of the first conventional art.
FIG. 6 shows the connector for the towing vehicle disclosed in U.S. Pat. No. 5,800,188. In this second conventional art, the connection portion 11 of the connector to be connected with the trailer-side connector (not shown) is formed cylindrically. Normally, the connector (not shown) at the towing vehicle body side is rectangular. Thus to connect the connector at the towing vehicle body side and the trailer-side connector to each other directly, the opposite-side connection portion 12 of the connector to be connected to the connector at the towing vehicle body side is formed rectangularly. However, in the second conventional art, no waterproof measure is taken for the connector at the towing vehicle body side.
FIG. 7 shows the connector for the towing vehicle of the third conventional art. The connector for the towing vehicle is the standard product of USCAR (US Conference of Automotive Research). The connection portion 21 of the connector (not shown) to be connected to the connection portion 21 at the towing vehicle body side and the connection portion 22 thereof to be connected to the trailer-side connector (not shown) are formed cylindrically. Although not shown, the gap formed on the periphery of metal pieces 23 inserted into the connector, is sealed from water with a sealing medium made of silicon to secure waterproofness.
In the first conventional art, the screw 2 is tightened to fix the electric wires 1 extending from the towing vehicle body to the terminals 3a to be inserted into the connector body 3. Thus the screw 2 may be loosened due to travel-caused vibrations, which may lead to failure of contact between the electric wires 1 and the terminals 3a inside the connector body 3.
The electric wires 1 are clamped one by one to the terminals 3 inside the connector body 3 with the screw 2. Thus, it takes much time to assemble the connector for the towing vehicle and the manufacturing cost is high.
Further waterproofness of the connector is not considered in the first conventional art. Thus there is a possibility that water penetrates into the portion of connection between the terminals 3a and the electric wires 1 and hence electrically conductive portions, such as metal pieces, are corroded. Thus, this connector for the towing vehicle has problems in reliability and durability.
In the second conventional art, the connection portion 11 of the connector to be connected with the trailer-side connector is formed cylindrically. On the other hand, the connection portion 12 of the connector to be connected to the connector at the towing vehicle body side is rectangular. Thus it is necessary to prepare metal pieces for terminals in different configurations so that the metal pieces can be arranged at corresponding positions in the cylindrical connection portion 11 and the rectangular connection portion 12 respectively and to connect the metal pieces in the connection portions 11 and 12 to each other. Therefore the manufacturing cost is high.
Further waterproofness of the connector of the second conventional art is not considered. Thus, this connector for the towing vehicle has problems in reliability and durability.
In the third conventional art, unlike the second conventional art, both the connection portion 22 of the connector to be connected to the trailer-side connector (not shown) and the connection portion 21 thereof to be connected to the connector at the towing vehicle body side are cylindrical. Thus terminals to be inserted into the connection portions 21 and 22 can be arranged smoothly at corresponding positions. Therefore it is possible to use the same metal pieces 23 penetrating through the connection portions 21 and 22 and the number of the metal pieces 23 is lower than that of the connector of the second conventional art.
However, in the connector of the third conventional art, the commercially available rectangular connectors cannot be used for the connector at the towing vehicle body side. Thus it is necessary to prepare the cylindrical exclusive connectors, which increases the manufacturing cost.
In the connector of the third conventional art, the sealing medium made of silicon is applied to the gap on the periphery of the metal pieces 23 inserted into the connector to secure waterproofness of the connector. However, it is necessary to inject the sealing medium deep into the connector. Therefore the sealing medium is liable to attach to the surface of the metal pieces 23. It is very difficult to visually detect the sealing medium that has attached to the surface thereof. Accordingly it is difficult to secure the connector having stable quality.
The hardening period of time of the sealing medium made of silicon that is used in the third conventional art is long after it is applied to the gap.
In any of the connector of the first, second, and third conventional arts, electric wires of the wire harness, at the towing vehicle body side, to be connected to the connectors are partly exposed. Thus when a stone or the like strikes electric wires during travel of the towing vehicle, they may be damaged.
In view of the above-described problems, it is a first object of the present invention to provide a connector for a towing vehicle that can be manufactured at a low cost. It is a second object to improve waterproofness of the connector for the towing vehicle to thereby prevent an electrically conductive portion from being corroded and protect electric wires effectively. It is a third object to improve the quality of the connector for the towing vehicle.
The invention is a connector for a towing vehicle including a housing formed of an approximately cylindrical first connection body disposed at a rear side of the housing to be connected to a wire harness of a to-be-towed object. An approximately cylindrical second connection body is disposed at a front side of the housing and is to be connected to a wire harness of a towing vehicle body. A first terminal is disposed inside the housing in a range from a portion of connection between the first connection body and the second connection body and is connected to a connector of the wire harness of the to-be-towed object. A second terminal is disposed inside the housing in a range from the portion of connection between the first connection body and the second connection body and is connected to the wire harness of the towing vehicle body. A terminal holder is fitted on an inner periphery of the portion of connection between the first connection body and the second connection body, for holding the first terminal and the second terminal.
In this construction, the first terminal is formed of one end portion of a metal piece; and the second terminal is formed of the other end portion of the metal piece.
Preferably, the connector further includes a first waterproof means fitted between an inner periphery of the housing and a periphery of the terminal holder for making inside the housing waterproof.
Preferably, the connector further includes a waterproof thermosetting sealing medium applied to a gap between the terminal holder and the metal piece.
The end of a core wire of the wire harness of the towing vehicle body preferably has the coating material torn therefrom and the second connector is connected to the end of the core.
A waterproof member preferably is mounted on the end of the wiring harness for preventing water from penetrating into a portion of connection between the second terminal and the core wire.
Preferably, the connector further includes a protector covering the second connection body and an insertion portion of the wire harness of the towing vehicle body into the second connection body, with an end of the wire harness of the towing vehicle body inserted into the second connection body.
Preferably, a bellows-shaped corrugate tube is mounted on a periphery of the wire harness of the towing vehicle body; and a part of an inner periphery of the protector is formed in correspondence to a configuration of the corrugate tube.
The invention also relates to a method of manufacturing a connector for a towing vehicle. The method includes the steps of mounting a metal piece on a terminal holder; applying a sealing medium to a gap between the terminal holder and the metal piece; hardening the sealing medium by overheating the sealing material; and fitting the terminal holder into a housing.